Model systems of coppercontaining enzymes based on benzimidazole-containing ligands

Die Dissertation beschäftigt sich mit verschiedenen Kupferkomplexen in den Oxidationsstufe +I und +II, die als Modellsysteme für in der Natur vorkommende Kupferproteine dienen. Dazu wurde eine Vielzahl von benzimidazolhaltigen Liganden synthetisiert, und mit verschiedenen Kupfersalzen umgesetzt. Die erhaltenen Komplexe wurden charakterisiert und mittels elektrochemischer Methoden untersucht. Zudem wurden auch oxidationsunempfindliche Silber(I)komplexe der entsprechenden Liganden dargestellt und charakterisiert.The Ph.D. Thesis was written about a variaty of different copper complexes in the oxidation states +I and +II, which are used as models for naturally exisiting copperproteins. Therefor a huge number of benzimidazolecontainig ligands have been synthesized and reacted with different copper salts. The complexes obtained were fully charakterized and further investigated with electrochemical methods. In addition a number of oxidationinsensitve silver(I)complexes were synthsized and charakterized

Ancillary ligand determination of the spin location in both oxidised and reduced forms of diruthenium complexes bridged by bis-bidentate 1,4-bis(2-phenolato)-1,4-diazabutadiene

The rare bridging mode of 1,4-bis(2-phenolato)-1,4-diazabutadiene = glyoxalbis(2-hydroxyanil) (L2-) is adopted in {(mu-L2-)[Ru-II(bpy)(2)](2)}(2+) (1(2+)), obtained as bis-perchlorate. Four well accessible redox forms of 1(n) (n = 4+, 3+, 2+, +) have been characterised by UV-VIS-NIR spectroelectrochemistry. The (3+) and (+) intermediates have also been investigated by EPR, both showing radical-type signals close to g = 2. This observation stands in stark contrast to EPR results previously obtained for the related {(mu-L)[Ru(acac)(2)](2)}(n), n = + and -, both of which exhibit metal-centred spin. In combination with the UV-VIS-NIR spectra these results suggest the preferential involvement of the multistep ligand redox system Ln- in the electron transfer processes. The relative stabilisation of Ru-II by pi-accepting bpy is made responsible for the oxidation of the ligand L2- instead of the metal

Synthesis, characterization and structure of tribromo(2-phenyl-1,8- naphthyridine)gold(III)

Neutral tribromo(2-phenyl-1,8-naphthyridine)gold(III), AuBr 3(N-N), has been prepared by reaction of KAuBr4 with the ligand in CHCl3/C2H5OH and was characterized by 1H NMR spectroscopy and X-ray diffraction. The molecular and crystal structure of AuBr3(N-N) · 0.5 THF (triclinic, P1-, a = 11.314(2), b = 12.350(3), c = 14.628(3) Å , α = 107.96(3), β = 98.86(3), γ = 107.29(3)°, Z = 4, 173 K) shows coordination of the N8 nitrogen atom situated in the unsubstituted pyridine ring to the planar four-coordinate AuIII center. Whereas the AuBr 3N best planes and the coordinated naphthyridine rings are not far from orthogonal (ω ∼ 105°), the phenyl substituents were found in the crystal with a ca. 22° dihedral angle relative to the naphthyridine plane. Intermolecular Au⋯Br distances close to the sum of the van der Waals radii indicate very weak interactions to form a quasi-dimeric arrangement in the crystal. © 2011 Verlag der Zeitschrift für Naturforschung, Tübingen